1. Field of the Invention
This invention relates to an ultra-sonic automatic flaw detection device which detects automatically any defects in a material to be probed such as steel material, etc. by use of, for example, an ultra-sonic searching unit as a sensor.
2. Description of Prior Art
As a device of this kind, there has so far been known such one as shown in FIG. 1 of the accompanying drawing.
In the drawing, a reference numeral 1 designates a supporting frame which supports the entire device; a numeral 2 refers to a bearing supporter mounted on the supporting frame 1; a numeral 3 refers to a hollow shaft which is fitted and supported in a freely rotatable manner on this bearing supporter 2 through bearings 4, 4 such as, for example, ball bearings, etc., and through the interior of which passes a material 5 to be probed. The bearings 4, 4 are disposed in the neighborhood of both end parts of the hollow shaft 3. A numeral 6 refers to a signal transmission device which is interposed between the bearing supporters 2, 2, confronts to the hollow shaft 3, and transmits flaw detection signals from ultra-sonic searching units 9 to be mentioned later to the outside. The signal transmission device 6 is constructed with a rotor section 6a mounted on and around the outer periphery of the hollow shaft 3 between the bearings 4, 4 and a stator section 6b fixed on the supporting frame 1 in a manner to be opposite to the rotor section 6a, both these sections being made electrically cooperative. A reference numeral 7 designates a flaw detection signal repeater mounted on one end part of the hollow shaft 3. A reference numeral 8 designates a holder for searching units, which extends in the axial direction and opposite to the hollow shaft 3 through the flaw detection signal repeater 7, and rotates in association with rotation of the hollow shaft 3. A numeral 9 refers to a sensor comprising ultra-sonic searching units incorporated in the searching unit holder 8 (the sensor will hereinafter be called "ultra-sonic searching unit"). A reference numeral 10 denotes a water supply device which is mounted on the bearing supporter 2 at the other end part of the hollow shaft 3, and is to supply water for the flaw detection into a space gap between the ultra-sonic searching units 9 and the material 5 to be probed through a water supply passage formed consecutively in the hollow shaft 3, the flaw detection signal repeater 7, and the searching unit holder 8. A reference numeral 11 represents a belt pulley which is fitted on and around the outer periphery of the hollow shaft 3 at the other end part thereof; a numeral 12 refers to a drive motor mounted on one part of the supporting frame 1; a reference numeral 13 designates a belt extended between the rotational shaft of the drive motor 12 and the belt pulley 11; and a numeral 14 refers to pinch rollers to perform alignment of the material 5 to be probed.
In the following, the operations of the conventional automatic flaw detection device of the above-described construction will be explained. The ultra-sonic automatic flaw detection device is installed in a inspection line for the material 5 to be probed, such as steel material, so that the materials may pass sequentially through it. First of all, the drive motor 12 is actuated to rotate the hollow shaft 3 through the belt 13 and the belt pulley 11. In association with rotation of this hollow shaft 3, there rotate both searching unit holder 8 mounted on the hollow shaft 3 through the flaw detection signal repeater 7 and the ultra-sonic searching units 9 embedded in the searching unit holder 8. In the next place, a material 5 to be probed is conveyed from the inspection line and passes through the center of the searching unit holder 8 after alignment of the material 5 to be probed by way of the pinch rollers 14, 14. During passage of the material 5 to be probed through the center of the searching unit holder 8, water for the flaw detection is supplied from the water supply device 10 so as to fill the space gap between the ultra-sonic searching units 9 and the material 5 to be probed. By thus causing the material 5 to be probed to pass through the center of the searching unit holder 8 in rotation, the material 5 to be probed is sensed in a spiral form by means of the ultra-sonic searching units 9 embedded in the searching unit holder 8. The flaw detection signals from the ultra-sonic searching units 9 are transmitted from the rotor section 6a of the signal transmission device 6 to the stator section 6b through the flaw detection signal repeater 7, and then led outside.
With the above-described conventional device, however, the searching unit holder 8 extends in the longitudinal direction of and opposite to the hollow shaft 3, that is, it is mounted outwardly of the device in a jut-out condition, with the consequent elongation of the total length of the device. Accordingly, the spacing for arranging the pinch rollers 14, 14 becomes wide, and, when the distal end of the material 5 to be probed is about to pass through the searching unit holder 8 as shown in FIG. 3, if flexure or curving of the material 5 to be probed is large, it gets in contact with the searching unit holder 8 to make it impossible to carry out the flaw detection, and various other disadvantages.